An impassioned row over the right to die was ignited in Italy yesterday after a doctor admitted having disconnected the respirator of a man whose pleas for euthanasia had already stirred a national controversy.

Mario Riccio was questioned by police immediately after telling a press conference in Rome that he had switched off the life support system of a terminally ill muscular dystrophy sufferer. Piergiorgio Welby died late on Wednesday after his lawyers had fought an unsuccessful battle through the courts to have his life ended.

His death split Romano Prodi's centre-left government. The family policy minister, Rosy Bindi, said she felt "pity and respect" for Mr Welby, but added: "No law could - or will in future be able to - legitimise this case of euthanasia."

The Europe minister, Emma Bonino, however, took part in a press conference at which the ending of Mr Welby's life was defended. Earlier this week, she had hinted that his political supporters were "weighing up, together with him and his relatives, the possibility of an act of civil disobedience".

Euthanasia is illegal in Italy and those involved in Mr Welby's death could face a prison sentence of up to 15 years. His supporters have argued that the constitution gives patients a right to refuse medical treatment, but their arguments have been dismissed in the courts.

Luca Volonte, the chief whip of the conservative Christian Democrat Union in the lower house, called for the arrest of "the perpetrators of this murder". A group of MPs from Silvio Berlusconi's Forza Italia party signed a statement that the 60-year-old Mr Welby had died as the result of a "deliberate killing". And the former deputy prime minister and leader of the "post-fascist" National Alliance, Gianfranco Fini, said: "Whoever did it cannot but answer to the courts."

Piergiorgio Welby took some 40 minutes to die. Watched by the patient's wife, relatives and friends, Dr Riccio administered an intravenous cocktail of sedatives and then removed the respirator keeping Mr Welby alive.

One of those present said his final words were "Thank you. Thank you. Thank you."

The Vatican's views on the sanctity of life are overwhelming endorsed in Italy, even by many who are not practising Roman Catholics. But the publicity given to Mr Welby's plight appeared to have caused many to reassess their attitudes.

His case had been widely reported since September when he appealed directly to the head of state, President Giorgio Napolitano. "I find the idea of dying horrible," he wrote. "But what is left to me is no longer a life." Mr Welby, who was fed through a tube and spoke through a voice synthesiser, said his existence had become "unbearable torture".